Question 2.20: Door Opener A driveway gate shown in Figure 2.48 is driven b...
Door Opener
A driveway gate shown in Figure 2.48 is driven by an electric motor that is connected to a voltage source of 200 V. In order to move the driveway gate, a force of 500 N or more is required. Assume that the motor drives the driveway gate at a constant speed of 0.2 ms^{−1} and that the gate path is 4 m long. Also, assume that the power required to start the motor is the same as the power required to move the gate. Calculate the total power that will be required for this process, and the possible resistance in the motor.
Here, force, F = 500 N, velocity, V_e = 0.2 ms^{−1} , and distance, d = 4 m. Thus, the total time of the process is t = d/V_e= 20 s. In addition, we can calculate the power needed as:
P=\frac{Fd}{t}=100 WTo calculate the resistance, we can use the following equation:
P=\frac{V^2}{R}Given that V = 200 V, and the result of the power calculation (P = 100 W), we see that the resistance corresponds to R = 400 Ω.